Assessment of annual soil loss and soil erosion susceptibility in a tropical sub-basin of the Western Ghats, Southern India using RUSLE and AHP
The Western Ghats (WG) of southern India represent a geomorphologically sensitive terrain where soil erosion and landslides constitute major geohazards. The Chittar sub-basin (CSB) of the Achankovil River Basin (ARB) was selected for investigation owing to its steep slopes, high-intensity rainfall, and increasing anthropogenic pressure, which together accentuate erosional processes. This study employs remote sensing and GIS techniques in conjunction with the Analytical Hierarchy Process (AHP) and the Revised Universal Soil Loss Equation (RUSLE) to quantify annual soil loss and delineate erosion susceptibility zones. High erosion affects 684.11 ha (24.8%) of the basin, whereas low erosion is observed across 780.03 ha (28.3%). Multicriteria evaluation indicates that vegetation cover (NDVI), rainfall, soil texture, soil depth, slope, aspect, and elevation exert the greatest influence on erosion susceptibility. Spatial analysis reveals that the western sector of the basin is most vulnerable, the central region exhibits moderate susceptibility, and the northwestern part remains comparatively stable. The results provide a process-based understanding of erosion dynamics in tropical high-relief basins and furnish a decision-support framework for prioritizing soil and water conservation strategies in the WG.